1. Field of the Invention
The present invention relates to an ink tank for a liquid jet recording apparatus that records by discharging ink. More particularly, the invention relates to an ink tank having a plurality of joint portions with respect to the ink jet printing system that consumes a large amount of ink.
2. Related Background Art
An ink tank (a liquid container) used for an ink jet recording apparatus is structured to be detachably mountable on an ink tank unit, which is an ink tank installing portion of the recording apparatus, in order to make it easier to exchange ink tanks when ink is consumed. For the ink tank, the ink supply port is arranged with a rubber plug or the like for the prevention of ink leakage when dealing with the ink tank as an individual body at the time of deliver or exchange thereof. At the same time, a hollow needle or the like is arranged for the ink tank unit for use of the connection with the ink tank, which makes the ink supply possible from the ink tank when it is connected with the ink supply port of the ink tank.
For the inner structure of the ink tank, there have been known various modes, such as the one that retains ink in the sponge or the some others material that generate capillary force, the one that retains ink in a flexible bag, or the one that retains ink directly in a rigid housing. Particularly, for the recording apparatus arranged to make a steady ink supply by keeping the water head difference constant between the head and the liquid surface of the tank by use of tubes or the like to connect the recording head and the ink tank, it is preferable to adopt the structure arranged to contain ink directly in the tank housing also from the viewpoint that this structure makes the reduction of part numbers possible.
The ink tank that adopts the aforesaid structure is provided with the communication port with the air outside for releasing the interior of the housing to the atmosphere when supplying ink. This communication port with the air outside is also sealed with closing means, such as a rubber plug, in order to prevent the ink leakage or the like when the ink tank is handled as an individual body. This closing means is arranged to be released when the ink tank is installed on the ink tank unit side.
However, for a larger type ink jet recording apparatus that consumes a large amount of ink due to the higher printing duty, a large capacity ink tank, such as 500 cc or more, is often used so as to suppress the frequency of the ink tank exchanges. Here, however, in order to adopt the aforesaid structure for such a large capacity ink tank as described above, it is required to manufacture the container itself in higher precision for the implementation of the reliable connection if the positioning section of the installation to the tank unit should be located away from the jointing portion, such as ink supply port or the communication port with the air outside. Here, a larger hollow container, which is capable of storing liquid directly in the interior thereof, is usually made with plastic by the blowing formation so as to provide the container at lower costs. Therefore, it is difficult to improve the dimensional precision of the container while maintaining the lower costs as usual.
Further, in recent years, it has been required to use plural kinds of ink having different densities or colorants for the implementation of the highly precise recording in higher image quality by use of the aforesaid apparatus. As a result, it is also required for the tank itself to be provided with a mechanism to prevent erroneous installation so that there is no possibility that a wrong ink tank is installed on the tank unit. As to such mechanism to prevent the erroneous installation, too, a higher precision is required, as the kinds of ink tanks, which should be installed on one tank unit, are increased. Then, for the recording apparatus for use of medical equipment, for use of the CAD outputs, for use of poster outputs, or for use of some other special purposes, it is required to make the precision higher still eventually for the mechanism on the tank side to prevent the erroneous installation if the tank unit should be arranged to be shareably usable by each of the apparatuses for the implementation of the lower-cost manufacture thereof, because the kinds of tanks that should be discriminated from one another become many inevitably in this case.